A. Field of the Invention
The present invention relates to a method for controlling a composite device and a composite device in which this method can be applied.
B. Related Art
More specifically the invention is intended to control a composite device that comprises at least a compressor installation, e.g., a compressor device, and/or drying device and a heat recovery system.
It is known that the compression of gas in a compressor installation is coupled with enormous heat generation.
Compressor installations are known with energy recovery means to recuperate this heat as efficiently as possible.
Traditionally compressors have been equipped with a basic regulation with the aim of controlling the compressor according to the demanded quantity of compressed air.
In known devices the coolant flow is controlled by means of a thermostatic valve on the output of the cooling circuit. It is thereby possible to control the flow of coolant such that the temperature at the output of the cooling circuit remains constant and is equal to a preset value.
When using a thermostatic valve, this preset value is a fixed value and it cannot be adjusted according to the heat consumption.
The temperature at the output of the cooling circuit will then always be the same, irrespective of the quantity of heat absorbed by the coolant.
A disadvantage is that neither the efficiency of the compressor installation nor the efficiency of the entire composite system is optimised.
Due to the absence of any form of optimisation, the composite device will then be subject to temperature fluctuations, for example.
Such temperature fluctuations are often undesirable and can also bring about premature wear of the device.
WP 2008/106774 describes a control of a system for recovering heat from a gas engine and converting heat into electricity. No account is taken here of the extent to which the optimisation of the heat recovery circuit affects the efficiency and reliability of the gas engine itself.